In the drilling industry, obtaining timely and accurate drilling information is a valuable tool in facilitating the efficient and economical formation of a bore hole. One way to obtain drilling information is by examining the earth-boring tool after it has been removed from the bore hole. This process is known in the oil drilling industry as “dull bit grading,” a process that has been standardized by the International Association of Drilling Contractors (IADC) Grading System.
The IADC Grading System uses a scale from zero to eight (0-8) to describe the condition of the cutting elements of an earth boring bit. For example, a steel toothed bit may have a measure of lost tooth height ranging from zero (no loss of tooth height) to eight (total loss of tooth height). Although this system provides standardization to the grading of dull bits and has the potential to provide valuable information to drillers, there are many shortcomings.
The system requires visual inspection of the bit and a subjective evaluation of cutting element loss based on the visual inspection. It may be difficult to determine the amount of cutting element loss due to wear and/or breakage by visual inspection alone. For example, cutting element loss may be difficult to quantify as the original shape of the cutting element may not be readily apparent when inspecting the dull tool. Even if the original cutting element shape is known, it may still be difficult to determine the amount of wear as the cutting element may have a rounded shape and/or the wear may be distributed over a large area of the cutting element. Some measurement tools have been developed to assist in determining cutting element loss, but they are often difficult to use, especially for an inexperienced operator. Additionally, even with the use of measurement tools, a significant amount of time may be required to determine an estimated amount of cutting element loss, and the estimated amount of cutting element loss may not be accurate.
If the amount of cutting element loss is not estimated accurately, the actual dull condition of the bit may not be accurately determined using the IADC Grading System. An improper determination of bit wear may result in a misdiagnosis of downhole conditions that may cause additional difficulty, waste, and/or expense in subsequent drilling with the tool that could have been avoided with an accurate evaluation of the dull bit.
In view of the shortcomings of the art, it would be advantageous to provide devices and methods that would facilitate an efficient, accurate, and objective determination of cutting element loss for earth-boring tools. Additionally, it would be advantageous to provide devices and methods that would facilitate the efficient and accurate objective determination of cutting element loss using visual inspection, and optionally without requiring use of separate measurement tools.